A plurality of chair controls have been provided in the past to support the seat and back rest of a stenographic type chair. These conventionally include a seat frame adapted to support the seat and fixed to the basic threaded vertical post. To provide for limited pivotal movement of the back rest as back pressure is placed upon it, a control member is mounted on the seat frame for limited pivotal movement. This control member is continually spring biased in a direction so as to urge the back rest in a forward direction, and conventionally this spring is adjustable to vary the tension on the back rest. A back strap is conventionally provided, sometimes with a vertical adjustment, fixed to the control member and projecting upwardly to a position where it directly supports the back rest.
There are two basic problems in these prior chair controls. The first is that the back rest has no positive attitude adjustment, and secondly, when the back strap fastener connecting it to the control member became loose or failed, the back strap and the back rest could easily fall from the chair causing injury to the user.